At what scale does the influence of humans on their surroundings end?

Question

This question is directed mostly at the "humans cannot influence the climate" group.

It's irrefutable that humans can alter the local surroundings, this has been documented through the urban heat island effect, poor forest management etc..

It's irrefutable that regional vegetation can influence climate via transpired water loss and albedo changes.  Humans have altered vegetation patterns in great swaths for the production of food resulting in changes in energy and mass balance.

Beyond the regional scale, things require more esoteric methods to quantify the impacts of interactions between humans and their environment.

So, the question is.  At which scale exactly (local, regional, continental or global) does the influence of humans on their surroundings diminish to a degree too small to measure?

And at the scale you feel the human influence ceases, is there a point at which an accumulation of influence at that level spills over into the next?

pegminer · Accepted Answer

In a material sense I guess it's about 121 astronomical units out from the sun, which is where Voyager is now.  It's thought that it may be going through the heliopause now, which would put it into interstellar space.

If we want to include electromagnetic emissions, then the scale becomes more than thousands of light years...not sure how far back human control of fire started, but that would probably be the date.

Phoenix Quill · Answer

And here I thought we were seeking the truth instead of defending a stance....

Every time I jump the Earth moves the other way. 
When I enter the ocean it rises.  Neptune affects the tides. 

Let's not pretend that 'humans cannot influence the climate' means anything besides the notion that our influence is too tiny to mater. 

So do I think the 0.01% change in CO2 attributed to humans is going to make the ocean rise a meter this next century,  oh hell no.   

AGW is a Religion to promote Socialism & your computer geeks are as pathological as the 20th century Eugenicists.  Lots of actual science going on, but when White People scientifically investigate if White People are superior, the conclusion is a given. 

And when people concerned about the damage man is doing to the environment scientifically investigate if their concerns are valid, the answer is always yes. 

We are prone to self aggrandizement & so it behooves us to practice humility.   Which is how I generally see the "we don't matter" statements. 

Now humans are quite creative  & as our knowledge grows, so does our power.   
So CAN we meaningfully change the Environment?
I would say the answer is yes.

But is our CO2 doing it?
The charts just don't suggest any meaningful sensitivity. 

http://www.youtube.com/watch?v=bKrw6ih8Gto

? · Answer

history is filled with failed civilizations that overreached their environment. 

As for how far....
we're certainly filling our earth orbital space with junk to the point collisions are a risk.
Sending radio and TV signals with junk programs for the last 100 years could expand our reach to about 100 light years from Earth.

Anonymous · Answer

A few humans could influence only a limited area. All of us together are changing atmospheric chemistry.

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At what scale does the influence of humans on their surroundings end?

4 Answers